Administrative access via cross-store JWT confusion
Published Sep 1, 2026 · Updated Sep 1, 2026
Privilege escalation in Cleo Harmony 5.8.1.0 through 5.8.1.10 allows remote attackers to gain administrative access via JWT replay. The refresh-token handler labels a token UNI_ADMIN while retaining a standard user's local identifier, then resolves that identifier against the separate administrator store during replay. Exploitation requires a token whose subject collides with an administrator username; a published chain obtains one through a separate SAML flaw.
Summary
What happened
Privilege escalation in Cleo Harmony 5.8.1.0 through 5.8.1.10 allows remote attackers to gain administrative access via JWT replay. The refresh-token handler labels a token UNI_ADMIN while retaining a standard user's local identifier, then resolves that identifier against the separate administrator store during replay. Exploitation requires a token whose subject collides with an administrator username; a published chain obtains one through a separate SAML flaw.
The record
- CVE
- CVE-2026-84115
- Published
- Sep 1, 2026
- Updated
- Sep 1, 2026
- Vendor
- Cleo
- Product
- Cleo Harmony
- Classifications
- CWE-266, CWE-269, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 1, 2026CVE publishedPublication date reported by the CVE source.
- Sep 1, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=5.8.1.0
- Affected versionversion=5.8.1.1
- Affected versionversion=5.8.1.10
- Affected versionversion=5.8.1.2
- Affected versionversion=5.8.1.3
- Affected versionversion=5.8.1.4
- Affected versionversion=5.8.1.5
- Affected versionversion=5.8.1.6
- Affected versionversion=5.8.1.7
- Affected versionversion=5.8.1.8
- Affected versionversion=5.8.1.9
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Cross-store identity lookup confusion HTTP proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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